/*
 * TI OMAP Real Time Clock interface for Linux
 *
 * Copyright (C) 2003 MontaVista Software, Inc.
 * Author: George G. Davis <gdavis@mvista.com> or <source@mvista.com>
 *
 * Copyright (C) 2006 David Brownell (new RTC framework)
 * Copyright (C) 2014 Johan Hovold <johan@kernel.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/pm_runtime.h>
#include <linux/io.h>
#include <linux/clk.h>

/*
 * The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
 * with century-range alarm matching, driven by the 32kHz clock.
 *
 * The main user-visible ways it differs from PC RTCs are by omitting
 * "don't care" alarm fields and sub-second periodic IRQs, and having
 * an autoadjust mechanism to calibrate to the true oscillator rate.
 *
 * Board-specific wiring options include using split power mode with
 * RTC_OFF_NOFF used as the reset signal (so the RTC won't be reset),
 * and wiring RTC_WAKE_INT (so the RTC alarm can wake the system from
 * low power modes) for OMAP1 boards (OMAP-L138 has this built into
 * the SoC). See the BOARD-SPECIFIC CUSTOMIZATION comment.
 */

/* RTC registers */
#define OMAP_RTC_SECONDS_REG            0x00
#define OMAP_RTC_MINUTES_REG            0x04
#define OMAP_RTC_HOURS_REG              0x08
#define OMAP_RTC_DAYS_REG               0x0C
#define OMAP_RTC_MONTHS_REG             0x10
#define OMAP_RTC_YEARS_REG              0x14
#define OMAP_RTC_WEEKS_REG              0x18

#define OMAP_RTC_ALARM_SECONDS_REG      0x20
#define OMAP_RTC_ALARM_MINUTES_REG      0x24
#define OMAP_RTC_ALARM_HOURS_REG        0x28
#define OMAP_RTC_ALARM_DAYS_REG         0x2c
#define OMAP_RTC_ALARM_MONTHS_REG       0x30
#define OMAP_RTC_ALARM_YEARS_REG        0x34

#define OMAP_RTC_CTRL_REG               0x40
#define OMAP_RTC_STATUS_REG             0x44
#define OMAP_RTC_INTERRUPTS_REG         0x48

#define OMAP_RTC_COMP_LSB_REG           0x4c
#define OMAP_RTC_COMP_MSB_REG           0x50
#define OMAP_RTC_OSC_REG                0x54

#define OMAP_RTC_KICK0_REG              0x6c
#define OMAP_RTC_KICK1_REG              0x70

#define OMAP_RTC_IRQWAKEEN              0x7c

#define OMAP_RTC_ALARM2_SECONDS_REG     0x80
#define OMAP_RTC_ALARM2_MINUTES_REG     0x84
#define OMAP_RTC_ALARM2_HOURS_REG       0x88
#define OMAP_RTC_ALARM2_DAYS_REG        0x8c
#define OMAP_RTC_ALARM2_MONTHS_REG      0x90
#define OMAP_RTC_ALARM2_YEARS_REG       0x94

#define OMAP_RTC_PMIC_REG               0x98

/* OMAP_RTC_CTRL_REG bit fields: */
#define OMAP_RTC_CTRL_SPLIT             BIT(7)
#define OMAP_RTC_CTRL_DISABLE           BIT(6)
#define OMAP_RTC_CTRL_SET_32_COUNTER    BIT(5)
#define OMAP_RTC_CTRL_TEST              BIT(4)
#define OMAP_RTC_CTRL_MODE_12_24        BIT(3)
#define OMAP_RTC_CTRL_AUTO_COMP         BIT(2)
#define OMAP_RTC_CTRL_ROUND_30S         BIT(1)
#define OMAP_RTC_CTRL_STOP              BIT(0)

/* OMAP_RTC_STATUS_REG bit fields: */
#define OMAP_RTC_STATUS_POWER_UP        BIT(7)
#define OMAP_RTC_STATUS_ALARM2          BIT(7)
#define OMAP_RTC_STATUS_ALARM           BIT(6)
#define OMAP_RTC_STATUS_1D_EVENT        BIT(5)
#define OMAP_RTC_STATUS_1H_EVENT        BIT(4)
#define OMAP_RTC_STATUS_1M_EVENT        BIT(3)
#define OMAP_RTC_STATUS_1S_EVENT        BIT(2)
#define OMAP_RTC_STATUS_RUN             BIT(1)
#define OMAP_RTC_STATUS_BUSY            BIT(0)

/* OMAP_RTC_INTERRUPTS_REG bit fields: */
#define OMAP_RTC_INTERRUPTS_IT_ALARM2   BIT(4)
#define OMAP_RTC_INTERRUPTS_IT_ALARM    BIT(3)
#define OMAP_RTC_INTERRUPTS_IT_TIMER    BIT(2)

/* OMAP_RTC_OSC_REG bit fields: */
#define OMAP_RTC_OSC_32KCLK_EN          BIT(6)
#define OMAP_RTC_OSC_SEL_32KCLK_SRC     BIT(3)

/* OMAP_RTC_IRQWAKEEN bit fields: */
#define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN BIT(1)

/* OMAP_RTC_PMIC bit fields: */
#define OMAP_RTC_PMIC_POWER_EN_EN       BIT(16)

/* OMAP_RTC_KICKER values */
#define KICK0_VALUE                     0x83e70b13
#define KICK1_VALUE                     0x95a4f1e0

struct omap_rtc;

struct omap_rtc_device_type {
        bool has_32kclk_en;
        bool has_irqwakeen;
        bool has_pmic_mode;
        bool has_power_up_reset;
        void (*lock)(struct omap_rtc *rtc);
        void (*unlock)(struct omap_rtc *rtc);
};

struct omap_rtc {
        struct rtc_device *rtc;
        void __iomem *base;
        struct clk *clk;
        int irq_alarm;
        int irq_timer;
        u8 interrupts_reg;
        bool is_pmic_controller;
        bool has_ext_clk;
        const struct omap_rtc_device_type *type;
};

static inline u8 rtc_read(struct omap_rtc *rtc, unsigned int reg)
{
        return readb(rtc->base + reg);
}

static inline u32 rtc_readl(struct omap_rtc *rtc, unsigned int reg)
{
        return readl(rtc->base + reg);
}

static inline void rtc_write(struct omap_rtc *rtc, unsigned int reg, u8 val)
{
        writeb(val, rtc->base + reg);
}

static inline void rtc_writel(struct omap_rtc *rtc, unsigned int reg, u32 val)
{
        writel(val, rtc->base + reg);
}

static void am3352_rtc_unlock(struct omap_rtc *rtc)
{
        rtc_writel(rtc, OMAP_RTC_KICK0_REG, KICK0_VALUE);
        rtc_writel(rtc, OMAP_RTC_KICK1_REG, KICK1_VALUE);
}

static void am3352_rtc_lock(struct omap_rtc *rtc)
{
        rtc_writel(rtc, OMAP_RTC_KICK0_REG, 0);
        rtc_writel(rtc, OMAP_RTC_KICK1_REG, 0);
}

static void default_rtc_unlock(struct omap_rtc *rtc)
{
}

static void default_rtc_lock(struct omap_rtc *rtc)
{
}

/*
 * We rely on the rtc framework to handle locking (rtc->ops_lock),
 * so the only other requirement is that register accesses which
 * require BUSY to be clear are made with IRQs locally disabled
 */
static void rtc_wait_not_busy(struct omap_rtc *rtc)
{
        int count;
        u8 status;

        /* BUSY may stay active for 1/32768 second (~30 usec) */
        for (count = 0; count < 50; count++) {
                status = rtc_read(rtc, OMAP_RTC_STATUS_REG);
                if (!(status & OMAP_RTC_STATUS_BUSY))
                        break;
                udelay(1);
        }
        /* now we have ~15 usec to read/write various registers */
}

static irqreturn_t rtc_irq(int irq, void *dev_id)
{
        struct omap_rtc *rtc = dev_id;
        unsigned long events = 0;
        u8 irq_data;

        irq_data = rtc_read(rtc, OMAP_RTC_STATUS_REG);

        /* alarm irq? */
        if (irq_data & OMAP_RTC_STATUS_ALARM) {
                rtc->type->unlock(rtc);
                rtc_write(rtc, OMAP_RTC_STATUS_REG, OMAP_RTC_STATUS_ALARM);
                rtc->type->lock(rtc);
                events |= RTC_IRQF | RTC_AF;
        }

        /* 1/sec periodic/update irq? */
        if (irq_data & OMAP_RTC_STATUS_1S_EVENT)
                events |= RTC_IRQF | RTC_UF;

        rtc_update_irq(rtc->rtc, 1, events);

        return IRQ_HANDLED;
}

static int omap_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);
        u8 reg, irqwake_reg = 0;

        local_irq_disable();
        rtc_wait_not_busy(rtc);
        reg = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
        if (rtc->type->has_irqwakeen)
                irqwake_reg = rtc_read(rtc, OMAP_RTC_IRQWAKEEN);

        if (enabled) {
                reg |= OMAP_RTC_INTERRUPTS_IT_ALARM;
                irqwake_reg |= OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN;
        } else {
                reg &= ~OMAP_RTC_INTERRUPTS_IT_ALARM;
                irqwake_reg &= ~OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN;
        }
        rtc_wait_not_busy(rtc);
        rtc->type->unlock(rtc);
        rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, reg);
        if (rtc->type->has_irqwakeen)
                rtc_write(rtc, OMAP_RTC_IRQWAKEEN, irqwake_reg);
        rtc->type->lock(rtc);
        local_irq_enable();

        return 0;
}

/* this hardware doesn't support "don't care" alarm fields */
static int tm2bcd(struct rtc_time *tm)
{
        if (rtc_valid_tm(tm) != 0)
                return -EINVAL;

        tm->tm_sec = bin2bcd(tm->tm_sec);
        tm->tm_min = bin2bcd(tm->tm_min);
        tm->tm_hour = bin2bcd(tm->tm_hour);
        tm->tm_mday = bin2bcd(tm->tm_mday);

        tm->tm_mon = bin2bcd(tm->tm_mon + 1);

        /* epoch == 1900 */
        if (tm->tm_year < 100 || tm->tm_year > 199)
                return -EINVAL;
        tm->tm_year = bin2bcd(tm->tm_year - 100);

        return 0;
}

static void bcd2tm(struct rtc_time *tm)
{
        tm->tm_sec = bcd2bin(tm->tm_sec);
        tm->tm_min = bcd2bin(tm->tm_min);
        tm->tm_hour = bcd2bin(tm->tm_hour);
        tm->tm_mday = bcd2bin(tm->tm_mday);
        tm->tm_mon = bcd2bin(tm->tm_mon) - 1;
        /* epoch == 1900 */
        tm->tm_year = bcd2bin(tm->tm_year) + 100;
}

static void omap_rtc_read_time_raw(struct omap_rtc *rtc, struct rtc_time *tm)
{
        tm->tm_sec = rtc_read(rtc, OMAP_RTC_SECONDS_REG);
        tm->tm_min = rtc_read(rtc, OMAP_RTC_MINUTES_REG);
        tm->tm_hour = rtc_read(rtc, OMAP_RTC_HOURS_REG);
        tm->tm_mday = rtc_read(rtc, OMAP_RTC_DAYS_REG);
        tm->tm_mon = rtc_read(rtc, OMAP_RTC_MONTHS_REG);
        tm->tm_year = rtc_read(rtc, OMAP_RTC_YEARS_REG);
}

static int omap_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);

        /* we don't report wday/yday/isdst ... */
        local_irq_disable();
        rtc_wait_not_busy(rtc);
        omap_rtc_read_time_raw(rtc, tm);
        local_irq_enable();

        bcd2tm(tm);

        return 0;
}

static int omap_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);

        if (tm2bcd(tm) < 0)
                return -EINVAL;

        local_irq_disable();
        rtc_wait_not_busy(rtc);

        rtc->type->unlock(rtc);
        rtc_write(rtc, OMAP_RTC_YEARS_REG, tm->tm_year);
        rtc_write(rtc, OMAP_RTC_MONTHS_REG, tm->tm_mon);
        rtc_write(rtc, OMAP_RTC_DAYS_REG, tm->tm_mday);
        rtc_write(rtc, OMAP_RTC_HOURS_REG, tm->tm_hour);
        rtc_write(rtc, OMAP_RTC_MINUTES_REG, tm->tm_min);
        rtc_write(rtc, OMAP_RTC_SECONDS_REG, tm->tm_sec);
        rtc->type->lock(rtc);

        local_irq_enable();

        return 0;
}

static int omap_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);
        u8 interrupts;

        local_irq_disable();
        rtc_wait_not_busy(rtc);

        alm->time.tm_sec = rtc_read(rtc, OMAP_RTC_ALARM_SECONDS_REG);
        alm->time.tm_min = rtc_read(rtc, OMAP_RTC_ALARM_MINUTES_REG);
        alm->time.tm_hour = rtc_read(rtc, OMAP_RTC_ALARM_HOURS_REG);
        alm->time.tm_mday = rtc_read(rtc, OMAP_RTC_ALARM_DAYS_REG);
        alm->time.tm_mon = rtc_read(rtc, OMAP_RTC_ALARM_MONTHS_REG);
        alm->time.tm_year = rtc_read(rtc, OMAP_RTC_ALARM_YEARS_REG);

        local_irq_enable();

        bcd2tm(&alm->time);

        interrupts = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
        alm->enabled = !!(interrupts & OMAP_RTC_INTERRUPTS_IT_ALARM);

        return 0;
}

static int omap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);
        u8 reg, irqwake_reg = 0;

        if (tm2bcd(&alm->time) < 0)
                return -EINVAL;

        local_irq_disable();
        rtc_wait_not_busy(rtc);

        rtc->type->unlock(rtc);
        rtc_write(rtc, OMAP_RTC_ALARM_YEARS_REG, alm->time.tm_year);
        rtc_write(rtc, OMAP_RTC_ALARM_MONTHS_REG, alm->time.tm_mon);
        rtc_write(rtc, OMAP_RTC_ALARM_DAYS_REG, alm->time.tm_mday);
        rtc_write(rtc, OMAP_RTC_ALARM_HOURS_REG, alm->time.tm_hour);
        rtc_write(rtc, OMAP_RTC_ALARM_MINUTES_REG, alm->time.tm_min);
        rtc_write(rtc, OMAP_RTC_ALARM_SECONDS_REG, alm->time.tm_sec);

        reg = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
        if (rtc->type->has_irqwakeen)
                irqwake_reg = rtc_read(rtc, OMAP_RTC_IRQWAKEEN);

        if (alm->enabled) {
                reg |= OMAP_RTC_INTERRUPTS_IT_ALARM;
                irqwake_reg |= OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN;
        } else {
                reg &= ~OMAP_RTC_INTERRUPTS_IT_ALARM;
                irqwake_reg &= ~OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN;
        }
        rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, reg);
        if (rtc->type->has_irqwakeen)
                rtc_write(rtc, OMAP_RTC_IRQWAKEEN, irqwake_reg);
        rtc->type->lock(rtc);

        local_irq_enable();

        return 0;
}

static struct omap_rtc *omap_rtc_power_off_rtc;

/*
 * omap_rtc_poweroff: RTC-controlled power off
 *
 * The RTC can be used to control an external PMIC via the pmic_power_en pin,
 * which can be configured to transition to OFF on ALARM2 events.
 *
 * Notes:
 * The two-second alarm offset is the shortest offset possible as the alarm
 * registers must be set before the next timer update and the offset
 * calculation is too heavy for everything to be done within a single access
 * period (~15 us).
 *
 * Called with local interrupts disabled.
 */
static void omap_rtc_power_off(void)
{
        struct omap_rtc *rtc = omap_rtc_power_off_rtc;
        struct rtc_time tm;
        unsigned long now;
        u32 val;

        rtc->type->unlock(rtc);
        /* enable pmic_power_en control */
        val = rtc_readl(rtc, OMAP_RTC_PMIC_REG);
        rtc_writel(rtc, OMAP_RTC_PMIC_REG, val | OMAP_RTC_PMIC_POWER_EN_EN);

        /* set alarm two seconds from now */
        omap_rtc_read_time_raw(rtc, &tm);
        bcd2tm(&tm);
        rtc_tm_to_time(&tm, &now);
        rtc_time_to_tm(now + 2, &tm);

        if (tm2bcd(&tm) < 0) {
                dev_err(&rtc->rtc->dev, "power off failed\n");
                return;
        }

        rtc_wait_not_busy(rtc);

        rtc_write(rtc, OMAP_RTC_ALARM2_SECONDS_REG, tm.tm_sec);
        rtc_write(rtc, OMAP_RTC_ALARM2_MINUTES_REG, tm.tm_min);
        rtc_write(rtc, OMAP_RTC_ALARM2_HOURS_REG, tm.tm_hour);
        rtc_write(rtc, OMAP_RTC_ALARM2_DAYS_REG, tm.tm_mday);
        rtc_write(rtc, OMAP_RTC_ALARM2_MONTHS_REG, tm.tm_mon);
        rtc_write(rtc, OMAP_RTC_ALARM2_YEARS_REG, tm.tm_year);

        /*
         * enable ALARM2 interrupt
         *
         * NOTE: this fails on AM3352 if rtc_write (writeb) is used
         */
        val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
        rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG,
                        val | OMAP_RTC_INTERRUPTS_IT_ALARM2);
        rtc->type->lock(rtc);

        /*
         * Wait for alarm to trigger (within two seconds) and external PMIC to
         * power off the system. Add a 500 ms margin for external latencies
         * (e.g. debounce circuits).
         */
        mdelay(2500);
}

static struct rtc_class_ops omap_rtc_ops = {
        .read_time      = omap_rtc_read_time,
        .set_time       = omap_rtc_set_time,
        .read_alarm     = omap_rtc_read_alarm,
        .set_alarm      = omap_rtc_set_alarm,
        .alarm_irq_enable = omap_rtc_alarm_irq_enable,
};

static const struct omap_rtc_device_type omap_rtc_default_type = {
        .has_power_up_reset = true,
        .lock           = default_rtc_lock,
        .unlock         = default_rtc_unlock,
};

static const struct omap_rtc_device_type omap_rtc_am3352_type = {
        .has_32kclk_en  = true,
        .has_irqwakeen  = true,
        .has_pmic_mode  = true,
        .lock           = am3352_rtc_lock,
        .unlock         = am3352_rtc_unlock,
};

static const struct omap_rtc_device_type omap_rtc_da830_type = {
        .lock           = am3352_rtc_lock,
        .unlock         = am3352_rtc_unlock,
};

static const struct platform_device_id omap_rtc_id_table[] = {
        {
                .name   = "omap_rtc",
                .driver_data = (kernel_ulong_t)&omap_rtc_default_type,
        }, {
                .name   = "am3352-rtc",
                .driver_data = (kernel_ulong_t)&omap_rtc_am3352_type,
        }, {
                .name   = "da830-rtc",
                .driver_data = (kernel_ulong_t)&omap_rtc_da830_type,
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(platform, omap_rtc_id_table);

static const struct of_device_id omap_rtc_of_match[] = {
        {
                .compatible     = "ti,am3352-rtc",
                .data           = &omap_rtc_am3352_type,
        }, {
                .compatible     = "ti,da830-rtc",
                .data           = &omap_rtc_da830_type,
        }, {
                /* sentinel */
        }
};
MODULE_DEVICE_TABLE(of, omap_rtc_of_match);

static int omap_rtc_probe(struct platform_device *pdev)
{
        struct omap_rtc *rtc;
        struct resource *res;
        u8 reg, mask, new_ctrl;
        const struct platform_device_id *id_entry;
        const struct of_device_id *of_id;
        int ret;

        rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
        if (!rtc)
                return -ENOMEM;

        of_id = of_match_device(omap_rtc_of_match, &pdev->dev);
        if (of_id) {
                rtc->type = of_id->data;
                rtc->is_pmic_controller = rtc->type->has_pmic_mode &&
                                of_property_read_bool(pdev->dev.of_node,
                                                "system-power-controller");
        } else {
                id_entry = platform_get_device_id(pdev);
                rtc->type = (void *)id_entry->driver_data;
        }

        rtc->irq_timer = platform_get_irq(pdev, 0);
        if (rtc->irq_timer <= 0)
                return -ENOENT;

        rtc->irq_alarm = platform_get_irq(pdev, 1);
        if (rtc->irq_alarm <= 0)
                return -ENOENT;

        rtc->clk = devm_clk_get(&pdev->dev, "ext-clk");
        if (!IS_ERR(rtc->clk))
                rtc->has_ext_clk = true;
        else
                rtc->clk = devm_clk_get(&pdev->dev, "int-clk");

        if (!IS_ERR(rtc->clk))
                clk_prepare_enable(rtc->clk);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        rtc->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(rtc->base))
                return PTR_ERR(rtc->base);

        platform_set_drvdata(pdev, rtc);

        /* Enable the clock/module so that we can access the registers */
        pm_runtime_enable(&pdev->dev);
        pm_runtime_get_sync(&pdev->dev);

        rtc->type->unlock(rtc);

        /*
         * disable interrupts
         *
         * NOTE: ALARM2 is not cleared on AM3352 if rtc_write (writeb) is used
         */
        rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG, 0);

        /* enable RTC functional clock */
        if (rtc->type->has_32kclk_en) {
                reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
                rtc_writel(rtc, OMAP_RTC_OSC_REG,
                                reg | OMAP_RTC_OSC_32KCLK_EN);
        }

        /* clear old status */
        reg = rtc_read(rtc, OMAP_RTC_STATUS_REG);

        mask = OMAP_RTC_STATUS_ALARM;

        if (rtc->type->has_pmic_mode)
                mask |= OMAP_RTC_STATUS_ALARM2;

        if (rtc->type->has_power_up_reset) {
                mask |= OMAP_RTC_STATUS_POWER_UP;
                if (reg & OMAP_RTC_STATUS_POWER_UP)
                        dev_info(&pdev->dev, "RTC power up reset detected\n");
        }

        if (reg & mask)
                rtc_write(rtc, OMAP_RTC_STATUS_REG, reg & mask);

        /* On boards with split power, RTC_ON_NOFF won't reset the RTC */
        reg = rtc_read(rtc, OMAP_RTC_CTRL_REG);
        if (reg & OMAP_RTC_CTRL_STOP)
                dev_info(&pdev->dev, "already running\n");

        /* force to 24 hour mode */
        new_ctrl = reg & (OMAP_RTC_CTRL_SPLIT | OMAP_RTC_CTRL_AUTO_COMP);
        new_ctrl |= OMAP_RTC_CTRL_STOP;

        /*
         * BOARD-SPECIFIC CUSTOMIZATION CAN GO HERE:
         *
         *  - Device wake-up capability setting should come through chip
         *    init logic. OMAP1 boards should initialize the "wakeup capable"
         *    flag in the platform device if the board is wired right for
         *    being woken up by RTC alarm. For OMAP-L138, this capability
         *    is built into the SoC by the "Deep Sleep" capability.
         *
         *  - Boards wired so RTC_ON_nOFF is used as the reset signal,
         *    rather than nPWRON_RESET, should forcibly enable split
         *    power mode.  (Some chip errata report that RTC_CTRL_SPLIT
         *    is write-only, and always reads as zero...)
         */

        if (new_ctrl & OMAP_RTC_CTRL_SPLIT)
                dev_info(&pdev->dev, "split power mode\n");

        if (reg != new_ctrl)
                rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);

        /*
         * If we have the external clock then switch to it so we can keep
         * ticking across suspend.
         */
        if (rtc->has_ext_clk) {
                reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
                rtc_write(rtc, OMAP_RTC_OSC_REG,
                          reg | OMAP_RTC_OSC_SEL_32KCLK_SRC);
        }

        rtc->type->lock(rtc);

        device_init_wakeup(&pdev->dev, true);

        rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
                        &omap_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc->rtc)) {
                ret = PTR_ERR(rtc->rtc);
                goto err;
        }

        /* handle periodic and alarm irqs */
        ret = devm_request_irq(&pdev->dev, rtc->irq_timer, rtc_irq, 0,
                        dev_name(&rtc->rtc->dev), rtc);
        if (ret)
                goto err;

        if (rtc->irq_timer != rtc->irq_alarm) {
                ret = devm_request_irq(&pdev->dev, rtc->irq_alarm, rtc_irq, 0,
                                dev_name(&rtc->rtc->dev), rtc);
                if (ret)
                        goto err;
        }

        if (rtc->is_pmic_controller) {
                if (!pm_power_off) {
                        omap_rtc_power_off_rtc = rtc;
                        pm_power_off = omap_rtc_power_off;
                }
        }

        return 0;

err:
        device_init_wakeup(&pdev->dev, false);
        rtc->type->lock(rtc);
        pm_runtime_put_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);

        return ret;
}

static int __exit omap_rtc_remove(struct platform_device *pdev)
{
        struct omap_rtc *rtc = platform_get_drvdata(pdev);
        u8 reg;

        if (pm_power_off == omap_rtc_power_off &&
                        omap_rtc_power_off_rtc == rtc) {
                pm_power_off = NULL;
                omap_rtc_power_off_rtc = NULL;
        }

        device_init_wakeup(&pdev->dev, 0);

        if (!IS_ERR(rtc->clk))
                clk_disable_unprepare(rtc->clk);

        rtc->type->unlock(rtc);
        /* leave rtc running, but disable irqs */
        rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);

        if (rtc->has_ext_clk) {
                reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
                reg &= ~OMAP_RTC_OSC_SEL_32KCLK_SRC;
                rtc_write(rtc, OMAP_RTC_OSC_REG, reg);
        }

        rtc->type->lock(rtc);

        /* Disable the clock/module */
        pm_runtime_put_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int omap_rtc_suspend(struct device *dev)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);

        rtc->interrupts_reg = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);

        rtc->type->unlock(rtc);
        /*
         * FIXME: the RTC alarm is not currently acting as a wakeup event
         * source on some platforms, and in fact this enable() call is just
         * saving a flag that's never used...
         */
        if (device_may_wakeup(dev))
                enable_irq_wake(rtc->irq_alarm);
        else
                rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
        rtc->type->lock(rtc);

        /* Disable the clock/module */
        pm_runtime_put_sync(dev);

        return 0;
}

static int omap_rtc_resume(struct device *dev)
{
        struct omap_rtc *rtc = dev_get_drvdata(dev);

        /* Enable the clock/module so that we can access the registers */
        pm_runtime_get_sync(dev);

        rtc->type->unlock(rtc);
        if (device_may_wakeup(dev))
                disable_irq_wake(rtc->irq_alarm);
        else
                rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, rtc->interrupts_reg);
        rtc->type->lock(rtc);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(omap_rtc_pm_ops, omap_rtc_suspend, omap_rtc_resume);

static void omap_rtc_shutdown(struct platform_device *pdev)
{
        struct omap_rtc *rtc = platform_get_drvdata(pdev);
        u8 mask;

        /*
         * Keep the ALARM interrupt enabled to allow the system to power up on
         * alarm events.
         */
        rtc->type->unlock(rtc);
        mask = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG);
        mask &= OMAP_RTC_INTERRUPTS_IT_ALARM;
        rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, mask);
        rtc->type->lock(rtc);
}

static struct platform_driver omap_rtc_driver = {
        .probe          = omap_rtc_probe,
        .remove         = __exit_p(omap_rtc_remove),
        .shutdown       = omap_rtc_shutdown,
        .driver         = {
                .name   = "omap_rtc",
                .pm     = &omap_rtc_pm_ops,
                .of_match_table = omap_rtc_of_match,
        },
        .id_table       = omap_rtc_id_table,
};

module_platform_driver(omap_rtc_driver);

MODULE_ALIAS("platform:omap_rtc");
MODULE_AUTHOR("George G. Davis (and others)");
MODULE_LICENSE("GPL");